The instant invention relates to thermostatic valves, and more particularly to a thermostatic valve which is operative with increased accuracy for restricting the flow of a fluid therethrough when the valve is in an open position.
Thermostatic valves which are operative in response to predetermined temperature conditions for movement between open and closed positions have been generally known for a number of years. Further, thermostatic valves which are actuated in response to predetermined temperature conditions by temperature responsive bimetallic discs for movement between open and closed positions have also been generally known for a number of years. In this regard the U.S. Pat. Nos. #1,654,519; to GREENAWALT, #1,773,698; SPENCER, #3,930,613 PLACE, and #4,103,824, to SEIFERT, disclose exemplary thermostatic valves which are actuated by bimetallic discs.
One specific type of heretofore available thermostatic valve which has been generally found to be effective comprises a valve body having an interior cavity formed therein, inlet and outlet passages in the valve body which communicate with the cavity, a valve seat in the valve body adjacent the outlet passage, and a bimetallic disc in the cavity adjacent the valve seat. The bimetallic disc has at least one aperture formed therein which is offset from the center of the disc, and the disc is responsive to a predetermined temperature condition for movement between a first position wherein the central portion of the disc is flexed toward the valve seat so that it substantially prevents the flow of fluid through the outlet passage, and a second position wherein the central portion of the disc is flexed away from the valve seat so that fluid can pass from the cavity to the outlet passage by passing through the aperture in the disc. Further, the bimetallic disc of a valve of this type is mounted so that the peripheral portion thereof is movable in the cavity in the valve body when the disc is flexed in response to a predetermined temperature condition. More specifically, the disc is mounted so that when the central portion thereof is flexed toward the valve seat, the peripheral portion of the disc is free to move in a direction away from the plane of the valve seat and so that when the central portion of the disc is flexed away from the valve seat, the peripheral portion of the disc is free to move in a direction toward the plane of the valve seat. Further, the disc is mounted on a disc seat which is substantially coplanar with the valve seat so that when the valve is in the open position, fluid flowing through the valve causes the peripheral portion of the disc to be moved into engagement with the disc seat. Accordingly, when the valve is in the open position, the central portion of the disc is only spaced from the valve seat by the amount of curvature in the disc when it is in an inwardly flexed position.
In has been found that while valves of the above-described type are normally designed so that the aperture or apertures in the discs thereof function as flow restricting orifices, other resistances often limit the effectiveness of the apertures in the discs of valves of this type to accurately restrict fluid flows. More specifically, it has been found that substantial resistances can occur as a fluid passes between the one or more apertures in the disc of a valve of this type and the outlet passage of the valve due to the close tolerances between the central portion of the disc and the valve seat of the valve. In this regard, it should be recognized that when the disc of a valve of this type is in the open position, the central portion of the bimetallic disc is only spaced from the adjacent valve seat by the amount of curvature in the disc and that therefore the spacing between the central portion of the disc and the valve seat can be significantly less than the area of the one or more apertures in a bimetallic disc. Further, since the aperture or apertures in a bimetallic disc of a valve of this type must inherently be offset in nonaligned relation with respect to the adjacent valve seat, a fluid passing through the aperture or apertures must pass in close tolerances between the bimetallicdisc of the valve and the adjacent portion of the valve body before passing through the outlet passage. Accordingly, it has been found that significant resistances to fluid flow can occur in a valve of this type between the aperture or apertures in the bimetallic disc thereof and the outlet passage thereof. It has been further found that the amounts of these resistances can be unpredictable and that they can have serious detrimental effects on the accuracy with which the aperture or apertures in the bimetallic disc of a valve of this type can function for accurately restricting fluid flow.
The instant invention provides an effective thermostatic valve which is generally similar to the valve hereinabove set forth but which is operative with substantially increased accuracy for reducing the flow resistance through the valve when the valve is in the open position. Specifically, the valve of the instant invention comprises a valve body having an interior cavity formed therein and having first and second passages which communicate with the cavity and with the exterior of the valve body for passing fluids therebetween, a valve seat in the valve body at the inner end of the first passage, and a bimetallic disc mounted in the cavity adjacent the valve seat. The bimetallic disc has at least one aperture therethrough, and it is mounted and oriented so that it is responsive to a predetermined temperature condition for flexing between a closed position wherein the central portion of the disc engages the valve seat for preventing the flow of fluid therethrough, and an open position wherein the central portion of the disc is spaced from the valve seat so that fluid can flow between the first and second passages by passing through the aperture or apertures in the disc. The valve further comprises means for supporting the peripheral portion of the disc in inwardly spaced relation in the cavity from the plane of the valve seat in both the open and closed positions of the disc, and it preferably still further comprises means cooperating with the support means for maintaining the peripheral portion of the disc in a predetermined fixed position which is spaced inwardly in the cavity from the plane of the valve seat. The support means is preferably integrally formed with the bimetallic disc as either a peripheral rim or as a plurality of integrally formed feet which project toward the plane of the valve seat. The valve body is preferably further formed with a disc seat which extends in substantially coplanar relation around the valve seat, and the support means is preferably supported by the disc seat. Still further, in the preferred embodiment, the first passage in the valve body comprises an outlet passage, and the second passage comprises an inlet passage.
During use and operation of the valve of the subject invention, the bimetallic disc thereof is actuatable in response to a predetermined temperature condition for movement between open and closed positions, wherein the outlet passage is unobstructed and obstructed, respectively. However, because the support means supports the disc so that the peripheral portion thereof is maintained in inwardly spaced relation to the plane of the valve seat, an increased amount of spacing is provided between the central portion of the disc and the valve seat when the disc is in the open position. Hence, the resistance to the flow of a fluid passing between the aperture or apertures in the disc and the valve seat is substantially reduced. As a result, the aperture or apertures in the disc can effectively function for accurately restricting the flow of a fluid passing through the valve when the valve is in the open position.
Accordingly, it is a primary object of the instant invention to provide an improved bimetallic disc-actuated thermostatic valve.
Another object of the instant invention is to provide a thermostatic valve having an aperture in the bimetallic disc thereof which is effectively operative as an orifice for restricting the flow of a fluid through the valve when the valve is in an open position.
An even further object of the instant invention is to provide an effective bimetallic valve which is operative for accurately restricting the flow of a fluid therethrough when the valve is in the open position.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.